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EP4154047A1 - Scanned light beam video projection system and method, automotive vehicle head-up display and adaptive lighting device using such a system - Google Patents

Scanned light beam video projection system and method, automotive vehicle head-up display and adaptive lighting device using such a system

Info

Publication number
EP4154047A1
EP4154047A1 EP14828186.8A EP14828186A EP4154047A1 EP 4154047 A1 EP4154047 A1 EP 4154047A1 EP 14828186 A EP14828186 A EP 14828186A EP 4154047 A1 EP4154047 A1 EP 4154047A1
Authority
EP
European Patent Office
Prior art keywords
light
light beam
projection system
beams
sub
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14828186.8A
Other languages
German (de)
French (fr)
Inventor
Michael Irzyk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valeo Comfort and Driving Assistance SAS
Original Assignee
Valeo Comfort and Driving Assistance SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Valeo Comfort and Driving Assistance SAS filed Critical Valeo Comfort and Driving Assistance SAS
Publication of EP4154047A1 publication Critical patent/EP4154047A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
    • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
    • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
    • F21S41/16—Laser light sources
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
    • F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
    • F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
    • F21S41/176—Light sources where the light is generated by photoluminescent material spaced from a primary light generating element
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
    • F21S41/60—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by a variable light distribution
    • F21S41/67—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by a variable light distribution by acting on reflectors
    • F21S41/675—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by a variable light distribution by acting on reflectors by moving reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/101—Scanning systems with both horizontal and vertical deflecting means, e.g. raster or XY scanners
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
    • G02B27/102—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources
    • G02B27/104—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources for use with scanning systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/12—Beam splitting or combining systems operating by refraction only
    • G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2013—Plural light sources
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G03B21/204—LED or laser light sources using secondary light emission, e.g. luminescence or fluorescence
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2073—Polarisers in the lamp house
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3161—Modulator illumination systems using laser light sources
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3164—Modulator illumination systems using multiple light sources
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/317—Convergence or focusing systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/30—Semiconductor lasers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0905—Dividing and/or superposing multiple light beams

Definitions

  • the invention relates to a video projection system by scanning light beam.
  • the invention may for example be used in a projection or imaging apparatus, in which a light source produces a light beam which is associated with scanning means for forming an image, for example on a head-up display.
  • the light source of such a head-up display generally comes from one or more laser sources modulated by a video signal representative of the image to be displayed.
  • the invention can also be applied to an adaptive lighting device for a motor vehicle, using scanning means forming an image on a wavelength converting device, which in turn emits a modulated lighting light beam. function of said image.
  • the scanning means are made for example in the form of a MEMS-type micro-mirror or a matrix of such micro-mirrors, which require a beam of suitable size.
  • the invention aims to overcome at least some of the disadvantages of known video beam scanning video projection systems.
  • the invention also aims to provide a scanning video projection system for increasing the power of the light beam without generating heat dissipation problem.
  • the invention also aims to provide a scanning video projection system for increasing the power of the light beam without substantially changing the size of the light beam.
  • the invention relates to a video beam scanning system, characterized in that it comprises a device for emitting a light beam modulated by a video signal, and scanning means able to deviate said light beam to allow formation of a video image, the transmission device comprising at least two distinct light sources each emitting a substantially straight polarization light sub-beam, distinct from the other, and a recombination device configured to forming said light beam by combining the two sub-light beams, in the direction of the scanning means.
  • recombination device a device in which one can make to enter two light beams of different polarization direction so that these light beams are combined at the output of this device into a single light beam combining the polarization directions of the two input beams.
  • the invention thus makes it possible, by using two light sources rather than a single more powerful source, to reduce the problems of heat dissipation by limiting the power of each source, and by increasing the area available for heat dissipation. .
  • the combination of the two sub-light beams allows the formation of a light beam whose power is equal to the addition of the powers of the two sub-light beams, while maintaining a light beam size adapted to a video projection by scanning, in particular by reducing the phenomena of divergences.
  • the recombination device is a recombination prism.
  • recombination prism is meant a prism into which two light beams of different polarization directions can be input so that these light beams are combined at the output of this prism into a single light beam combining the polarization directions of the two beams. input.
  • the recombination prism is one of the following prisms:
  • these prisms which are generally used to divide a polarized light beam in two distinct directions into two beams each polarized in one of the two distinct directions, are here used for an opposite purpose, that is, that is to say the combination of two beams polarized in different directions of polarization into a single light beam polarized along these two directions.
  • the two sub-light beams have polarizations perpendicular to each other.
  • the combination of the two sub-beams is more efficient because of the minimal interference between the two light beams when their polarization directions are perpendicular.
  • the light sources are laser sources.
  • the light sources are laser sources which are naturally polarized, to avoid having to polarize the sub-light beams from these light sources before combining them, which can lead to power losses.
  • the laser sources have different frequency spectrums of power in the same narrow frequency band.
  • narrow frequency band is meant a frequency band in which the colors of the lasers at the frequencies of this band are not distinguishable by a human eye.
  • the spectra are different to avoid scab phenomena that can occur if the spectra of the two laser sources are identical, but they remain in a sufficiently narrow frequency band for the two lasers to have colors that are not differentiable so as not to damage the projected video image.
  • the sub-light beams are polychromatic sub-beams and the light sources are polychromatic sources.
  • the polychromatic sources allow video projection of images over a large color palette, by combination of monochromatic beams.
  • the two sub-light beams must be composed of the same color components to make it possible to obtain by combination a beam of the same color as the two preceding sub-beams.
  • each polychromatic light source comprises three monochromatic light sources, a red source emitting a red light beam, a green source emitting a green light beam and a blue source emitting a blue light beam, the beams red, green and blue are combined to form each polychromatic sub-beam.
  • the three sources red, green and blue make up a conventional system called RGB (for Red Green Blue) or RGB (for Red Green Blue in English) to obtain a large color palette by combination of three monochromatic beams emitted by monochromatic sources.
  • the invention also relates to a display, in particular a head-up display, comprising a projection system according to the invention.
  • Such a display can be used in a vehicle, especially a motor vehicle, to display the video image projected by the projection system.
  • the invention also relates to an adaptive lighting device for a motor vehicle, comprising a projection system according to the invention.
  • the lighting device further comprises a wavelength conversion device, on which an image is formed by the projection system, the conversion device emitting a beam thus modulated according to said image.
  • the invention also relates to a method of video projection by scanning light beam, characterized in that it comprises a step of emitting a light beam modulated by a video signal, a step of deflecting said light beam by scanning to enable the formation of a video image, the step of emitting a light beam being preceded by a step of combining two distinct light sub-beams and substantially straight polarization, distinct from one another, to form said light beam.
  • the method according to the invention is implemented by the system according to the invention.
  • system according to the invention implements the method according to the invention.
  • FIG. 1 is a schematic representation of the operation of a recombination prism of a projection system according to one embodiment of the invention
  • FIG. 2 is a schematic representation of a projection system according to one embodiment of the invention.
  • FIG. 3 is a schematic representation of a polychromatic light source according to one embodiment of the invention.
  • FIG. 4 represents a schematic view of a video projection system and a head-up display according to one embodiment of the invention
  • FIG. 5 shows a schematic view of a video projection system and an adaptive lighting device according to one embodiment of the invention.
  • FIG. 1 schematically represents the operation of a recombination prism 12 that can be used as a recombination device in one embodiment of the video projection system according to the invention.
  • the recombination prism 12 is configured to interact differently with the light beams passing therethrough as a function of the polarization thereof.
  • Examples of Classically recombinant prisms are Glan-Taylor prisms, Glan- Thompson prisms, Nicol prisms, and so on.
  • the prism represented here is a prism of Wollaston. All of these prisms are generally used to separate an unpolarized light beam into two light beams having perpendicular polarization directions.
  • the recombination prism 12 is used in a different way, that is to say for combining two perpendicular polarization direction light sub-beams 16, 16, 17 to form a light beam 18 combining the two polarization directions of the two sub-beams 14, 15.
  • FIG. 2 represents a video projection system 100 according to one embodiment of the invention.
  • the projection system 100 comprises a light beam emitting device 1 and scanning means 20 which deflect the light beam 18 to form a video image 22.
  • the transmission device 1 comprises two light sources, a first light source 24 emitting a first light sub-beam 14 and a second light source 25 emitting a second light sub-beam 15.
  • the two sub-beams 14, 15 are directed towards a recombination device, here the recombination prism 12 described with reference to FIG. 1.
  • the two sub-beams 14, 15 have different directions of polarization, here one perpendicular to the other in order to optimize the optical efficiency and to reduce the interferences between the two sub-beams 14, 15 during recombination. the prism 12.
  • the first sub-beam 14 has a substantially straight and horizontal direction of polarization 16, represented by a double arrow
  • the second sub-beam 15 has a substantially straight and vertical direction of polarization 17, represented by a dot.
  • the two sub-beams 14, 15 merge into a single beam 18, polarized in the two polarization directions of the two sub-light beams, as represented by the reference 26.
  • the light sources 24, 25 used are laser sources, typically laser diodes, which have the advantage of being naturally polarized. As shown in FIG. 2, the directions in which the beams 14, 15 must enter in the recombination prism 12 cause the sources 24 to move away ; 25. This distance makes it possible to increase the heat dissipation surface and thus to avoid heating the components due to the optical power required for the projection system 100 to project the image 22. Moreover, each source 24, 25 has a power half of the optical power required for the projection of the image 22.
  • each source 24, 25 emits a beam 14, 15 of optical power of 50 mW, which makes it possible to obtain a recombined beam 18 of 100 mW.
  • the laser sources 24, 25 have different frequency spectrums of power in the same narrow frequency band, ie a frequency band in which the colors of the lasers at the frequencies of this band are not not differentiable by a human eye. This makes it possible to avoid scab phenomena that may occur if the spectra of the two laser sources are identical, but they remain close enough so that the two lasers have non-differentiable colors so as not to damage the projected video image.
  • the beam 18 For video image projection requiring a light beam 18 having a wide range of possible colors, the beam 18 must be a polychromatic beam, i.e. it consists of a combination of monochromatic beams.
  • each light source 24, 25 is therefore a polychromatic source which comprises several monochromatic light sources, here three monochromatic sources, a red source emitting a red beam, a green source emitting a green beam and a blue source emitting a blue beam. These three red, green and blue beams are combined to form the polychromatic sub-beams. Due to the presence of these multiple monochromatic light sources to form each sub-beam, the improvement of the heat dissipation provided by the invention is all the more necessary for the proper operation of the projection system 100.
  • FIG. 3 illustrates more in. detail the operation of one of the polychromatic light sources.
  • the polychromatic light source 28 comprises one or more monochromatic light sources 4, 5, 6 each emitting a beam 7, 8, 9 of the laser type. These are, for example, laser sources, typically laser diodes, each laser source emitting a monochromatic beam, that is to say consisting of a single color. In one embodiment of the invention, this polychromatic source 28 is therefore used to form each of the light sources 24 and 25.
  • the polychromatic source 28 here comprises three monochromatic sources 4,
  • said device being configured to form a polychromatic light beam 10 by pooling by combining the monochromatic beams 7, 8, 9 individually emitted by each of the sources 4, 5, 6. More specifically, it may be monochromatic sources emitting a beam of a different color from one source to another, for example, a red, a green or a blue (RGB or RGB,) emitted respectively by a red diode, a green diode or a blue diode.
  • RGB or RGB red, a green or a blue
  • the optical power of each of the monochromatic sources is driven, independently, using the supply current of the laser source or sources.
  • the color of the polychromatic beam 10 is determined by how a power ratio is established between the different laser diodes. For example, to obtain a white light, the optical powers, in proportion, must be established according to the following distribution: 60% for the green diode, 30% for the blue diode, 10% for the red diode.
  • the optical power of each of the monochromatic sources can also be controlled to modulate the optical power of the polychromatic beam 10.
  • the beams 7, 8, 9 emitted by each of the monochromatic sources are oriented, for example, parallel to each other and reflected in the same direction to form by combination the common polychromatic beam 10.
  • the polychromatic source here comprises in this sense elements semi-transparent optics, over a range of wavelengths, such as dichroic mirrors or combination blades 11, intercepting the monochromatic beams 7, 8, 9 emitted by each of the monochromatic sources and combining them in the direction of the polychromatic beam 10 .
  • the polychromatic source 28 is configured to form the polychromatic beam 10 from the monochromatic laser beam (s) 7, 8, 9 irrespective of the number of monochromatic sources 4, 5, 6 involved.
  • the beam 10 is composed of the laser beam emitted by the only source used and the resulting image will then be monochrome, composed of the different levels of optical power applied to each of the points that compose it, according to a gradient of said color.
  • the common beam 10 which then forms the polychromatic beam will allow the establishment of an image according to a color spectrum whose resolution will correspond to the fineness of control of the supply of said monochromatic sources 4, 5, 6.
  • the video projection system also comprises attenuation means 13 situated downstream of the source or sources 4, 5, 6, making it possible to vary the optical power of the light beam 10.
  • the attenuation means 13 make it possible to vary the optical power of the beam (s) 7, 8, 9, 10.
  • the optical power of the beam can be adapted to daytime running conditions and night driving conditions, for the application of the system. in a head-up display of a motor vehicle.
  • the polychromatic source 28 may comprise means for controlling the power supply of the monochromatic sources. As mentioned above, they may allow a choice of the color of the beam 10.
  • control means are configured, for example, to provide a linear current regulation of the optical power of the monochromatic laser beams 7, 8, 9 so as to ensure the color selection of the polychromatic beam 10, in a proportion of optical power allocated to each of the monochromatic laser beams 7, 8, 9.
  • control means may also be configured to provide additional adjustment of the optical power of the light beam. In this way, a particularly high attenuation rate can be achieved.
  • control means are configured to provide pulse width modulation regulation of the optical power of the monochromatic laser beams 7, 8, 9 so as to perform the additional adjustment of the optical power of the polychromatic beam 10. in particular according to an attenuation factor of between 5 and 20, in particular of approximately 10.
  • control means comprise, for example, a microcontroller, not shown.
  • the invention also relates to a head-up display comprising a video projection system 100 according to the invention.
  • the projection system 100 further comprises means 102 for forming an image from the light beam 18 emitted by the transmission device 1.
  • the image forming means 102 comprise scanning means such as, for example, a scanning generator 110 whose function is to move the light beam 18 horizontally and vertically in order to perform a scanning at a given frequency, equal to 60 Hz as a non-limiting example.
  • the scanning generator 110 comprises, in particular, a scanning mirror with a microelectromechanical system (hereinafter referred to as the MEMS mirror) on which the light beam 18 is reflected in a scanning beam 103.
  • MEMS mirror microelectromechanical system
  • Such a MEMS mirror has, for example, a diameter 1 mm 2 .
  • the MEMS mirror is able to rotate around two axes of rotation to perform a scan, for example at the refresh rate of 60 Hz, a diffuser screen 111 of the means 102 for forming an image. Said image is then formed on the diffuser 111.
  • the MEMS mirror can be replaced by two plane and movable mirrors, whose movements are associated. One of these mirrors can be dedicated to a scan along a horizontal axis while the other mirror can be dedicated to a scan along a vertical axis.
  • the diffuser 111 where the image is formed may be a transparent projection screen with a complex structure for projection by transparency. It can alternatively be translucent. It is made, for example, of glass, especially frosted, or polycarbonate.
  • the diffuser screen is of the exit pupil type (Exit Pupil Expander). It allows to have an expanded observation cone. It extends in a plane traversed by the light beam, the image resulting from this scanning beam 103 being formed in the plane of a face of the diffuser screen 111. This diffuser screen receives the scanning beam 103.
  • a face 112 of the diffuser screen is rough, in that it has asperities that cause the dispersion of the scanning beam 103.
  • the rough face 112 corresponds to that through which the beam comes out, that is to say the face on which the image is formed.
  • said image forming means do not include a scanning generator, as described above, but a matrix of micro mirrors (also called Digital micro mirrors Systems in English).
  • the image is formed at the level of the mirror array and then projected onto the diffuser screen.
  • a projection optics is placed between the matrix and the screen.
  • Each micro mirror corresponds to a pixel of the image.
  • the image is not formed on the diffuser screen for the first time, but receives an image previously formed on the mirror array.
  • the attenuation means 13 of FIG. 3 may be arranged upstream of the imaging means 102. They can still be downstream. In a variant, they may be placed between the scanning generator 110 or the micro-mirror array, on the one hand, and the diffuser screen 111, on the other hand.
  • the projection system may also comprise different mirrors 104, 106 planes or concave so as to focus the beams to the diffuser screen 111, placed in particular on the trajectory of the scanning beam 103.
  • the invention also relates to a display, including a head-up, comprising a projection system 100 according to any of the variants detailed above.
  • the display Downstream of the diffuser screen 111 according to the direction of movement of the light beam, the display comprises at least one semi-reflective plate 126 and a reflection device 125 interposed on the path of the image between the diffuser screen 111 and the semi-reflecting plate 126, the reflection device 125 comprising one or more planar or concave mirrors, as shown in FIG. 4.
  • the path of the image is symbolized by three dotted arrows 30 which are reflected on the reflection device 125 before being displayed through the semi-reflecting blade 126.
  • This semi-reflective blade -reflective has a power of reflection at least equal to
  • the display of the image can take place at the windshield of the vehicle equipped with said display.
  • the invention also relates to an adaptive lighting device for a motor vehicle, comprising a video projection system 100 according to the invention.
  • the video projection system 100 comprises the transmission device 1, providing the combined beam 18, and the imaging means 102.
  • the means 102 in turn comprise the scanning means 110, providing a scanning beam 103, and optical means referenced 118, the type of the mirrors 104, 106 of Figure 4, for focusing the scanning beam on a device 113.
  • the beam at the output of the optical means 118 has the reference 115.
  • the element 113 is a wavelength conversion device such as a phosphor plate, or more exactly a plate on which has been deposited a continuous and homogeneous layer of phosphorus.
  • each point of the plate of the wavelength converting device 113 receiving the beam 115 then re-emits a beam 116, illustrated in dotted lines, of different wavelength, and in particular a light which can be considered as " white ", that is to say which has a plurality of wavelengths between about 400 nanometers and 800 nanometers, that is to say included in the spectrum of visible light.
  • This emission of light occurs, according to an emission diagram Lambertian, that is to say with a uniform luminous intensity in all directions.
  • the phosphor is deposited on a reflective substrate for the laser radiation.
  • the laser radiation which would not have encountered any phosphorus grain before having completely passed through the phosphor layer, could meet a grain of phosphorus after having been reflected by the substrate.
  • the substrate is selected from materials that are good thermal conductors.
  • the substrate is selected from materials that are good thermal conductors.
  • the surface of the wavelength conversion device consists of a continuous and homogeneous layer of phosphorus.
  • the partition of the phosphor plate into separate elements does not achieve the desired accuracy in the retransmission of white light, particularly at the points at the boundary between two phosphorus elements.
  • the phosphor plate 113 is located in the immediate vicinity of the focal plane of an imaging optical system 114, which then forms at infinity an image of the phosphor plate 113, or more exactly points of this plate that emit white light in response to the bright excitement they receive.
  • the imaging optical system 114 forms a light beam 117, also shown in dotted lines, with the light emitted by the various points of the phosphor plate illuminated by the radiation 115.
  • the light beam 117 emerging from the imaging system 114 is thus directly a function of the light rays 116 emitted by the phosphor plate 113, themselves directly dependent on the radiation 115 which scans the plate 113.
  • a control unit (not shown) controls the various components of the system according to the invention as a function of the desired photometry of the light beam 117. In particular, the control unit simultaneously controls:
  • the scanning means 110 for the beam 115 to successively scan all the points of the phosphor plate 113, and
  • the transmission device 1 for modulating the intensity of the beam 115 The transmission device 1 for modulating the intensity of the beam 115.
  • the intensity modulation can be performed continuously, the intensity increasing or decreasing continuously between a minimum value and a maximum value. It can also be performed discretely, the intensity varying in jumps from one value to another, between a minimum value and a maximum value. In both cases, it can be expected that the minimum value will be zero, corresponding to an absence of light.
  • Each point of the phosphor plate 113 thus illuminated by the beam 115 emits white light 116, with an intensity which is a direct function of the intensity of the beam which illuminates this point, the emission being effected according to a diagram of Lambertian emission.
  • the phosphor plate 113 can then be considered as a source of secondary radiation, consisting of a light image, whose optical imaging system 114 forms an image at infinity, for example on a screen placed at a distance in the axis of the optical system 114 and perpendicular to this axis.
  • the image on such a screen is the materialization of the light beam emitted by the optical system 114.
  • the beam 117 forms a lighting beam for a motor vehicle which is adaptive, that is to say whose light output is controllable point by point so as to be adapted to the environment of the vehicle.

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Abstract

The invention relates to a scanned light beam video projection system. The system is characterised in that it comprises a device (1) for emitting a light beam (18) modulated by a video signal, and scanning means (20) able to deviate said light beam (18) in order to allow a video image (22) to be formed, the emitting device (1) comprising at least two separate light sources (24, 25) each emitting a light sub-beam (14, 15) of different substantially rectilinear polarisation to the other, and a recombining device (12) configured to form said light beam (18) by adding the two light sub-beams (14, 15), in the direction of the scanning means (20).

Description

SYSTÈME ET PROCÉDÉ DE PROJECTION VIDÉO PAR BALAYAGE DE FAISCEAU LUMINEUX, AFFICHEUR TÊTE HAUTE ET DISPOSITIF D'ECLAIRAGE ADAPTATIF POUR  SYSTEM AND METHOD FOR LIGHT BEAM SCANNING VIDEO PROJECTION, HIGH HEAD DISPLAY AND ADAPTIVE LIGHTING DEVICE FOR
VEHICULE AUTOMOBILE UTILISANT UN TEL SYSTÈME 1. Domaine technique de l'invention  MOTOR VEHICLE USING SUCH A SYSTEM 1. Technical Field of the Invention
L'invention concerne un système de projection vidéo par balayage de faisceau lumineux.  The invention relates to a video projection system by scanning light beam.
L'invention pourra par exemple être utilisée dans un appareil de projection ou d'imagerie, dans lequel une source lumineuse produit un faisceau lumineux qui est associé à des moyens de balayage pour former une image, par exemple sur un afficheur tête haute. La source lumineuse d'un tel afficheur tête haute provient généralement d'une ou plusieurs sources laser modulées par un signal vidéo représentatif de l'image à afficher. The invention may for example be used in a projection or imaging apparatus, in which a light source produces a light beam which is associated with scanning means for forming an image, for example on a head-up display. The light source of such a head-up display generally comes from one or more laser sources modulated by a video signal representative of the image to be displayed.
L'invention pourra également s'appliquer à un dispositif d'éclairage adaptatif pour véhicule automobile, utilisant des moyens de balayage formant une image sur un dispositif de conversion de longueur d'onde, émettant à son tour un faisceau lumineux d'éclairage modulé en fonction de ladite image. The invention can also be applied to an adaptive lighting device for a motor vehicle, using scanning means forming an image on a wavelength converting device, which in turn emits a modulated lighting light beam. function of said image.
Les applications diverses des appareils utilisant un système de projection par balayage nécessitent l'utilisation de faisceaux lumineux de puissance optique de plus en plus importante pour en améliorer la performance, et donc des sources lumineuses de puissance plus importantes. Or, et particulièrement dans un système de projection par balayage de taille réduite, l'utilisation d'une source de trop grande puissance engendre des problèmes de dissipation thermique trop importante pouvant à leur tour entraîner des dégradations de la source elle-même ou des composants avoisinants. De tels systèmes de projection de taille réduite sont par exemple des systèmes em barqués, notamment dans un véhicule pour un afficheur dit tête haute. Le problème est d'autant plus important que le système utilise des sources de plusieurs couleurs pour former un faisceau polychromatique afin de projeter une image en couleur. Dans le cadre d'un système polychromatique classique utilisant trois faisceaux rouge, vert et bleu, il faut utiliser trois sources lumineuses ce qui augmente d'autant plus les problèmes de dissipation thermique. Outre les problèmes relatifs à la dissipation thermique, les sources lumineuses disponibles sur le marché adaptées aux contraintes des systèmes à balayage ont une puissance réduite. En outre, les solutions actuelles qui permettent l'augmentation de la puissance de ces sources ne sont pas utilisables dans un système à balayage, notamment pour des problèmes de taille du faisceau. En effet, les moyens de balayages sont réalisés par exemple sous la forme d'un micro-miroir de type MEMS ou d'une matrice de tels micro-miroirs, qui nécessitent un faisceau de taille adaptée. The various applications of devices using a scanning projection system require the use of light beams of optical power increasingly important to improve the performance, and therefore the larger light sources of power. However, and particularly in a reduced-size scanning projection system, the use of a source of excessive power generates problems of excessive heat dissipation which can in turn lead to damage to the source itself or components. nearby. Such reduced-size projection systems are, for example, emailed systems, in particular in a vehicle for a so-called head-up display. The problem is all the more important as the system uses sources of multiple colors to form a polychromatic beam to project a color image. As part of a conventional polychromatic system using three beams red, green and blue, it is necessary to use three light sources which increases even more the problems of heat dissipation. In addition to the problems relating to heat dissipation, light sources available on the market adapted to the constraints of scanning systems have reduced power. In addition, the current solutions that make it possible to increase the power of these sources can not be used in a scanning system, in particular for beam size problems. Indeed, the scanning means are made for example in the form of a MEMS-type micro-mirror or a matrix of such micro-mirrors, which require a beam of suitable size.
2. Objectifs de l'invention  2. Objectives of the invention
L'invention vise à pallier au moins certains des inconvénients des systèmes de projection vidéo par balayage de faisceau lumineux connus.  The invention aims to overcome at least some of the disadvantages of known video beam scanning video projection systems.
L'invention vise aussi à fournir un système de projection vidéo par balayage permettant l'augmentation de la puissance du faisceau lumineux sans générer de problème de dissipation thermique.  The invention also aims to provide a scanning video projection system for increasing the power of the light beam without generating heat dissipation problem.
L'invention vise aussi à fournir, un système de projection vidéo par balayage permettant l'augmentation de la puissance du faisceau lumineux sans modification substantielle de la taille du faisceau lumineux.  The invention also aims to provide a scanning video projection system for increasing the power of the light beam without substantially changing the size of the light beam.
3. Exposé de l'invention 3. Presentation of the invention
Pour ce faire, l'invention concerne un système de projection vidéo par balayage de faisceau lumineux, caractérisé en ce qu'il comprend un dispositif d'émission d'un faisceau lumineux modulé par un signal vidéo, et des moyens de balayage aptes à dévier ledit faisceau lumineux pour permettre la formation d'une image vidéo, le dispositif d'émission comprenant au moins deux sources lumineuses distinctes émettant chacune un sous-faisceau lumineux de polarisation sensiblement rectiligne, distincte de l'autre, et un dispositif de recombinaison configuré pour former ledit faisceau lumineux par combinaison des deux sous-faisceaux lumineux, en direction des moyens de balayage.  To do this, the invention relates to a video beam scanning system, characterized in that it comprises a device for emitting a light beam modulated by a video signal, and scanning means able to deviate said light beam to allow formation of a video image, the transmission device comprising at least two distinct light sources each emitting a substantially straight polarization light sub-beam, distinct from the other, and a recombination device configured to forming said light beam by combining the two sub-light beams, in the direction of the scanning means.
On entend par dispositif de recombinaison un dispositif dans lequel on peut faire entrer deux faisceaux lumineux de direction de polarisation différentes de telle façon à ce que ces faisceaux lumineux soient combinés en sortie de ce dispositif en un seul faisceau lumineux combinant les directions de polarisations des deux faisceaux d'entrée. By recombination device is meant a device in which one can make to enter two light beams of different polarization direction so that these light beams are combined at the output of this device into a single light beam combining the polarization directions of the two input beams.
L'invention permet ainsi, par l'utilisation de deux sources lumineuses plutôt qu'une unique source plus puissante, de réduire les problèmes de dissipation thermique par limitation de la puissance de chaque source, et par augmentation de la surface disponible pour la dissipation thermique. La combinaison des deux sous-faisceaux lumineux permet la formation d'un faisceau lumineux dont la puissance est égale à l'addition des puissances des deux sous-faisceaux lumineux, tout en conservant une taille de faisceau lumineux adaptée à une projection vidéo par balayage, en réduisant notamment les phénomènes de divergences.  The invention thus makes it possible, by using two light sources rather than a single more powerful source, to reduce the problems of heat dissipation by limiting the power of each source, and by increasing the area available for heat dissipation. . The combination of the two sub-light beams allows the formation of a light beam whose power is equal to the addition of the powers of the two sub-light beams, while maintaining a light beam size adapted to a video projection by scanning, in particular by reducing the phenomena of divergences.
Avantageusement et selon l'invention, le dispositif de recombinaison est un prisme de recombinaison. Advantageously and according to the invention, the recombination device is a recombination prism.
On entend par prisme de recombinaison un prisme dans lequel on peut faire entrer deux faisceaux lumineux de directions de polarisation différentes de façon à ce que ces faisceaux lumineux soient combinés en sortie de ce prisme en un seul faisceau lumineux combinant les directions de polarisations des deux faisceaux d'entrée. Avantageusement et selon ce dernier aspect de l'invention, le prisme de recombinaison est un des prismes suivant :  By recombination prism is meant a prism into which two light beams of different polarization directions can be input so that these light beams are combined at the output of this prism into a single light beam combining the polarization directions of the two beams. input. Advantageously and according to this last aspect of the invention, the recombination prism is one of the following prisms:
- prisme de Wollaston,  - Wollaston prism,
- prisme de Glan-Taylor,  - Glan-Taylor prism,
- prisme de Glan-Thompson,  - Glan-Thompson prism,
- prisme de Nicol.  - Nicol's prism.
Selon cet aspect de l'invention, ces prismes qui sont généralement utilisés pour diviser un faisceau lumineux polarisé selon deux directions distinctes en deux faisceaux polarisés chacun dans l'une des deux directions distinctes, sont ici utilisés pour un objectif opposé, c'est-à-dire la combinaison de deux faisceaux polarisés selon des directions de polarisation différentes en un faisceau lumineux unique polarisé selon ces deux directions. Avantageusement et selon l'invention, les deux sous-faisceaux lumineux ont des polarisations perpendiculaires l'une à l'autre. According to this aspect of the invention, these prisms, which are generally used to divide a polarized light beam in two distinct directions into two beams each polarized in one of the two distinct directions, are here used for an opposite purpose, that is, that is to say the combination of two beams polarized in different directions of polarization into a single light beam polarized along these two directions. Advantageously and according to the invention, the two sub-light beams have polarizations perpendicular to each other.
Selon cet aspect de l'invention, la combinaison des deux sous-faisceaux est plus efficace du fait de l'interférence minime entre les deux faisceaux lumineux lorsque leurs directions de polarisation sont perpendiculaires.  According to this aspect of the invention, the combination of the two sub-beams is more efficient because of the minimal interference between the two light beams when their polarization directions are perpendicular.
Avantageusement et selon l'invention, les sources lumineuses sont des sources lasers. Advantageously and according to the invention, the light sources are laser sources.
Selon cet aspect de l'invention, les sources lumineuses sont des sources lasers qui sont naturellement polarisées, pour éviter de devoir polariser les sous-faisceaux lumineux provenant de ces sources lumineuses avant de les combiner, ce qui peut entraîner des pertes de puissances.  According to this aspect of the invention, the light sources are laser sources which are naturally polarized, to avoid having to polarize the sub-light beams from these light sources before combining them, which can lead to power losses.
Avantageusement et selon ce dernier aspect de l'invention, les sources lasers ont des spectres fréquentiels de puissance différents dans une même bande de fréquence étroite.  Advantageously and according to this last aspect of the invention, the laser sources have different frequency spectrums of power in the same narrow frequency band.
On entend par bande de fréquence étroite une bande de fréquence dans laquelle les couleurs des lasers aux fréquences de cette bande ne sont pas différentiables par un œil humain.  By narrow frequency band is meant a frequency band in which the colors of the lasers at the frequencies of this band are not distinguishable by a human eye.
Selon cet aspect de l'invention, les spectres sont différents pour éviter les phénomènes de tavelures pouvant apparaître si les spectres des deux sources lasers sont identiques, mais ils restent compris dans une bande de fréquence suffisamment étroite pour que les deux lasers aient des couleurs non différentiables pour ne pas détériorer l'image vidéo projetée.  According to this aspect of the invention, the spectra are different to avoid scab phenomena that can occur if the spectra of the two laser sources are identical, but they remain in a sufficiently narrow frequency band for the two lasers to have colors that are not differentiable so as not to damage the projected video image.
Avantageusement et selon l'invention, les sous-faisceaux lumineux sont des sous-faisceaux polychromatiques et les sources lumineuses sont des sources polychromatiques. Advantageously and according to the invention, the sub-light beams are polychromatic sub-beams and the light sources are polychromatic sources.
Selon cet aspect de l'invention, les sources polychromatiques permettent une projection vidéo d'images sur une grande palette de couleurs, par combinaison de faisceaux monochromatiques. Toutefois dans ce cas, les deux sous-faisceaux lumineux doivent être composés des mêmes composantes de couleurs pour permettre d'obtenir par combinaison un faisceau de même couleur que les deux sous-faisceaux précédents. According to this aspect of the invention, the polychromatic sources allow video projection of images over a large color palette, by combination of monochromatic beams. However in this case, the two sub-light beams must be composed of the same color components to make it possible to obtain by combination a beam of the same color as the two preceding sub-beams.
Avantageusement et selon ce dernier aspect de l'invention, chaque source lumineuse polychromatique comprend trois sources lumineuses monochromatiques, une source rouge émettant un faisceau lumineux rouge, une source verte émettant un faisceau lumineux vert et une source bleue émettant un faisceau lumineux bleu, les faisceaux rouge, vert et bleu étant combinés pour former chaque sous-faisceau polychromatique.  Advantageously and according to this last aspect of the invention, each polychromatic light source comprises three monochromatic light sources, a red source emitting a red light beam, a green source emitting a green light beam and a blue source emitting a blue light beam, the beams red, green and blue are combined to form each polychromatic sub-beam.
Selon cet aspect de l'invention, les trois sources rouge, verte et bleue composent un système classique dit RVB (pour Rouge Vert Bleu) ou RGB (pour Red Green Blue en anglais) afin d'obtenir une grande palette de couleurs par combinaison des trois faisceaux monochromatiques émis par les sources monochromatiques.  According to this aspect of the invention, the three sources red, green and blue make up a conventional system called RGB (for Red Green Blue) or RGB (for Red Green Blue in English) to obtain a large color palette by combination of three monochromatic beams emitted by monochromatic sources.
L'invention concerne aussi un afficheur, notamment un afficheur tête haute, comprenant un système de projection selon l'invention. The invention also relates to a display, in particular a head-up display, comprising a projection system according to the invention.
Un tel afficheur peut être utilisé dans un véhicule, notamment un véhicule automobile, pour afficher l'image vidéo projetée par le système de projection.  Such a display can be used in a vehicle, especially a motor vehicle, to display the video image projected by the projection system.
L'invention concerne aussi un dispositif d'éclairage adaptatif pour véhicule automobile, comprenant un système de projection selon l'invention. The invention also relates to an adaptive lighting device for a motor vehicle, comprising a projection system according to the invention.
Avantageusement, le dispositif d'éclairage comprend en outre un dispositif de conversion de longueur d'onde, sur lequel est formée une image par le système de projection, le dispositif de conversion émettant un faisceau ainsi modulé en fonction de ladite image.  Advantageously, the lighting device further comprises a wavelength conversion device, on which an image is formed by the projection system, the conversion device emitting a beam thus modulated according to said image.
L'invention concerne également un procédé de projection vidéo par balayage de faisceau lumineux, caractérisé en ce qu'il comprend une étape d'émission d'un faisceau lumineux modulé par un signal vidéo, une étape de déviation dudit faisceau lumineux par balayage pour permettre la formation d'une image vidéo, l'étape d'émission d'un faisceau lumineux étant précédée d'une étape de combinaison de deux sous-faisceaux lumineux distincts et de polarisation sensiblement rectiligne, distinctes l'une de l'autre, pour former ledit faisceau lumineux. The invention also relates to a method of video projection by scanning light beam, characterized in that it comprises a step of emitting a light beam modulated by a video signal, a step of deflecting said light beam by scanning to enable the formation of a video image, the step of emitting a light beam being preceded by a step of combining two distinct light sub-beams and substantially straight polarization, distinct from one another, to form said light beam.
Avantageusement, le procédé selon l'invention est mis en oeuvre par le système selon l'invention.  Advantageously, the method according to the invention is implemented by the system according to the invention.
Avantageusement, le système selon l'invention met en uvre le procédé selon l'invention.  Advantageously, the system according to the invention implements the method according to the invention.
4. Description des figures 4. Description of the figures
D'autres buts, caractéristiques et avantages de l'invention apparaîtront à la lecture de la description suivante donnée à titre uniquement non limitatif et qui se réfère aux figures annexées, dans lesquelles :  Other objects, features and advantages of the invention will become apparent on reading the following description given solely by way of nonlimiting example and which refers to the appended figures, in which:
La figure 1 est une représentation schématique du fonctionnement d'un prisme de recombinaison d'un système de projection selon un mode de réalisation de l'invention,  FIG. 1 is a schematic representation of the operation of a recombination prism of a projection system according to one embodiment of the invention,
La figure 2 est une représentation schématique d'un système de projection selon un mode de réalisation de l'invention,  FIG. 2 is a schematic representation of a projection system according to one embodiment of the invention,
La figure 3 est une représentation schématique d'une source lumineuse polychromatique selon un mode de réalisation de l'invention,  FIG. 3 is a schematic representation of a polychromatic light source according to one embodiment of the invention,
La figure 4 représente une vue schématique d'un système de projection vidéo et d'un afficheur tête haute selon un mode de réalisation de l'invention,  FIG. 4 represents a schematic view of a video projection system and a head-up display according to one embodiment of the invention,
- La figure 5 représente une vue schématique d'un système de projection vidéo et d'un dispositif d'éclairage adaptatif selon un mode de réalisation de l'invention. - Figure 5 shows a schematic view of a video projection system and an adaptive lighting device according to one embodiment of the invention.
5. Description détaillée d'un mode de réalisation de l'invention 5. Detailed description of an embodiment of the invention
Il faut noter que les figures exposent l'invention de manière détaillée pour mettre en oeuvre l'invention, lesdites figures pouvant bien entendu servir à mieux définir l'invention le cas échéant.  It should be noted that the figures disclose the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate.
La figure 1 représente schématiquement le fonctionnement d'un prisme de recombinaison 12 pouvant être utilisé comme dispositif de recombinaison dans un mode de réalisation du système de projection vidéo selon l'invention. Le prisme de recombinaison 12 est configuré de façon à interagir différemment avec les faisceaux lumineux qui le traversent en fonction de la polarisation de ceux-ci. Des exemples de prismes de recombinaison classiques sont les prismes de Glan-Taylor, prismes de Glan- Thompson, prismes de Nicol, etc. Le prisme représenté ici est un prisme de Wollaston. Tous ces prismes sont en général utilisés pour séparer un faisceau lumineux non polarisé en deux faisceaux lumineux ayant des directions de polarisation perpendiculaires. FIG. 1 schematically represents the operation of a recombination prism 12 that can be used as a recombination device in one embodiment of the video projection system according to the invention. The recombination prism 12 is configured to interact differently with the light beams passing therethrough as a function of the polarization thereof. Examples of Classically recombinant prisms are Glan-Taylor prisms, Glan- Thompson prisms, Nicol prisms, and so on. The prism represented here is a prism of Wollaston. All of these prisms are generally used to separate an unpolarized light beam into two light beams having perpendicular polarization directions.
Dans un système selon un mode de réalisation de l'invention, le prisme de recombinaison 12 est utilisé de façon différente, c'est à dire pour combiner deux sous- faisceaux lumineux 14, 15 de direction de polarisation 16, 17 perpendiculaires afin de former un faisceau lumineux 18 combinant les deux directions de polarisations des deux sous-faisceaux 14, 15.  In a system according to one embodiment of the invention, the recombination prism 12 is used in a different way, that is to say for combining two perpendicular polarization direction light sub-beams 16, 16, 17 to form a light beam 18 combining the two polarization directions of the two sub-beams 14, 15.
La figure 2 représente un système de projection vidéo 100 selon un mode de réalisation de l'invention. Le système de projection 100 comprend un dispositif d'émission 1 d'un faisceau lumineux 18 et des moyens de balayage 20 qui dévient le faisceau lumineux 18 pour former une image vidéo 22. FIG. 2 represents a video projection system 100 according to one embodiment of the invention. The projection system 100 comprises a light beam emitting device 1 and scanning means 20 which deflect the light beam 18 to form a video image 22.
Le dispositif d'émission 1 comprend deux sources lumineuses, une première source lumineuse 24 émettant un premier sous-faisceau lumineux 14 et une deuxième source lumineuse 25 émettant un deuxième sous-faisceau lumineux 15. Les deux sous- faisceaux 14, 15 sont dirigés vers un dispositif de recombinaison, ici le prisme de recombinaison 12 décrit en référence à là figure 1.  The transmission device 1 comprises two light sources, a first light source 24 emitting a first light sub-beam 14 and a second light source 25 emitting a second light sub-beam 15. The two sub-beams 14, 15 are directed towards a recombination device, here the recombination prism 12 described with reference to FIG. 1.
Les deux sous-faisceaux 14, 15 présentent des directions de polarisations différentes, ici l'une perpendiculaire à l'autre afin d'optimiser le rendement optique et de réduire les interférences entre les deux sous-faisceaux 14, 15 lors de la recombinaison dans le prisme 12. Le premier sous-faisceau 14 a une direction de polarisation 16 sensiblement rectiligne et horizontale, représentée par une double flèche, et le deuxième sous-faisceau 15 a une direction de polarisation 17 sensiblement rectiligne et verticale, représentée par un point. En sortie du prisme de recombinaison 12, les deux sous-faisceaux 14, 15 sont confondus en un faisceau unique 18, polarisé dans les deux directions de polarisation des deux sous-faisceaux lumineux, comme représenté par la référence 26.  The two sub-beams 14, 15 have different directions of polarization, here one perpendicular to the other in order to optimize the optical efficiency and to reduce the interferences between the two sub-beams 14, 15 during recombination. the prism 12. The first sub-beam 14 has a substantially straight and horizontal direction of polarization 16, represented by a double arrow, and the second sub-beam 15 has a substantially straight and vertical direction of polarization 17, represented by a dot. At the output of the recombination prism 12, the two sub-beams 14, 15 merge into a single beam 18, polarized in the two polarization directions of the two sub-light beams, as represented by the reference 26.
Les sources lumineuses 24, 25 utilisées sont des sources lasers, typiquement des diodes lasers, qui ont pour avantage d'être naturellement polarisées. Comme représenté sur la figure 2, les directions dans lesquelles doivent entrer les faisceaux 14, 15 dans le prisme de recombinaison 12 entraînent un éloignement des sources 24; 25. Cet éloignement permet d'augmenter la surface de dissipation thermique et ainsi d'éviter réchauffement des composants dû à la puissance optique nécessaire au système de projection 100 pour projeter l'image 22. De plus, chaque source 24, 25 a une puissance optique égale à la moitié de la puissance optique nécessaire à la projection de l'image 22. Par exemple, si la projection de l'image 22 dans de bonnes conditions nécessite une puissance optique de 100 mW, chaque source 24, 25 émet un sous- faisceau 14, 15 de puissance optique de 50 mW, ce qui permet d'obtenir un faisceau 18 recombiné de 100 mW. The light sources 24, 25 used are laser sources, typically laser diodes, which have the advantage of being naturally polarized. As shown in FIG. 2, the directions in which the beams 14, 15 must enter in the recombination prism 12 cause the sources 24 to move away ; 25. This distance makes it possible to increase the heat dissipation surface and thus to avoid heating the components due to the optical power required for the projection system 100 to project the image 22. Moreover, each source 24, 25 has a power half of the optical power required for the projection of the image 22. For example, if the projection of the image 22 under good conditions requires an optical power of 100 mW, each source 24, 25 emits a beam 14, 15 of optical power of 50 mW, which makes it possible to obtain a recombined beam 18 of 100 mW.
Dans un mode de réalisation avantageux, les sources lasers 24, 25 ont des spectres fréquentiels de puissance différents dans une même bande de fréquence étroite, c'est à dire une bande de fréquence dans laquelle les couleurs des lasers aux fréquences de cette bande ne sont pas différentiables par un il humain. Cela permet d'éviter les phénomènes de tavelures pouvant apparaître si les spectres des deux sources lasers sont identiques, mais ils restent suffisamment proches pour que les deux lasers aient des couleurs non différentiables pour ne pas détériorer l'image vidéo projetée. Pour la projection d'image vidéo nécessitant un faisceau lumineux 18 ayant une large palette de couleurs possibles, le faisceau 18 doit être un faisceau polychromatique, c'est-à-dire qu'il se compose d'une combinaison de faisceaux monochromatiques. Dans un système de projection classique, on utilise une combinaison de trois faisceaux, un rouge, un vert et un bleu, de type RVB (pour Rouge, Vert, Bleu) ou RGB (pour Red Green Blue en anglais). Dans un système de projection selon ce mode de réalisation de l'invention, chaque source lumineuse 24, 25 est donc une source polychromatique qui comprend plusieurs sources lumineuses monochromatiques, ici trois sources monochromatiques, une source rouge émettant un faisceau rouge, une source verte émettant un faisceau vert et une source bleue émettant un faisceau bleu. Ces trois faisceaux rouge, vert et bleu sont combinés pour former les sous-faisceaux polychromatiques. Du fait de la présence de ces multiples sources lumineuses monochromatiques pour former chaque sous-faisceau, l'amélioration de la dissipation thermique apportée par l'invention est d'autant plus nécessaire au bon fonctionnement du système de projection 100. In an advantageous embodiment, the laser sources 24, 25 have different frequency spectrums of power in the same narrow frequency band, ie a frequency band in which the colors of the lasers at the frequencies of this band are not not differentiable by a human eye. This makes it possible to avoid scab phenomena that may occur if the spectra of the two laser sources are identical, but they remain close enough so that the two lasers have non-differentiable colors so as not to damage the projected video image. For video image projection requiring a light beam 18 having a wide range of possible colors, the beam 18 must be a polychromatic beam, i.e. it consists of a combination of monochromatic beams. In a conventional projection system, a combination of three beams, one red, one green and one blue, of type RGB (for Red, Green, Blue) or RGB (for Red Green Blue in English) is used. In a projection system according to this embodiment of the invention, each light source 24, 25 is therefore a polychromatic source which comprises several monochromatic light sources, here three monochromatic sources, a red source emitting a red beam, a green source emitting a green beam and a blue source emitting a blue beam. These three red, green and blue beams are combined to form the polychromatic sub-beams. Due to the presence of these multiple monochromatic light sources to form each sub-beam, the improvement of the heat dissipation provided by the invention is all the more necessary for the proper operation of the projection system 100.
La figure 3 illustre plus en. détail le fonctionnement d'une des sources lumineuses polychromatiques. Figure 3 illustrates more in. detail the operation of one of the polychromatic light sources.
La source lumineuse polychromatique 28 comprend une ou plusieurs sources lumineuses monochromatiques 4, 5, 6 émettant chacune un faisceau 7, 8, 9 du type laser. Il s'agit, par exemple, de sources laser, typiquement des diodes laser, chaque source laser émettant un faisceau monochromatique, c'est-à-dire consistant en une seule couleur. Dans un mode de réalisation de l'invention, cette source polychromatique 28 est donc utilisée pour former chacune des sources lumineuses 24 et 25. La source polychromatique 28 comprend ici trois sources monochromatiques 4, The polychromatic light source 28 comprises one or more monochromatic light sources 4, 5, 6 each emitting a beam 7, 8, 9 of the laser type. These are, for example, laser sources, typically laser diodes, each laser source emitting a monochromatic beam, that is to say consisting of a single color. In one embodiment of the invention, this polychromatic source 28 is therefore used to form each of the light sources 24 and 25. The polychromatic source 28 here comprises three monochromatic sources 4,
5, 6, ledit dispositif étant configuré pour former un faisceau lumineux polychromatique 10 à l'aide d'une mise en commun par combinaison des faisceaux monochromatiques 7, 8, 9 individuellement émis par chacune des sources 4, 5, 6. Plus précisément, il pourra s'agir de sources monochromatiques émettant un faisceau d'une couleur différente d'une source à l'autre, par exemple, un rouge, un vert ou un bleu (RVB ou RGB,) émis respectivement par une diode rouge, une diode verte ou une diode bleue. 5, 6, said device being configured to form a polychromatic light beam 10 by pooling by combining the monochromatic beams 7, 8, 9 individually emitted by each of the sources 4, 5, 6. More specifically, it may be monochromatic sources emitting a beam of a different color from one source to another, for example, a red, a green or a blue (RGB or RGB,) emitted respectively by a red diode, a green diode or a blue diode.
La puissance optique de chacune des sources monochromatiques est pilotée, de manière indépendante, à l'aide du courant d'alimentation de la ou des sources laser. A puissance optique donnée, la couleur du faisceau polychromatique 10 est déterminée par la manière dont un ratio de puissance est établi entre les différentes diodes laser. Par exemple, pour obtenir une lumière blanche, les puissances optiques, en proportion, doivent être établies selon la distribution suivante : 60% pour la diode verte, 30% pour la diode bleue, 10% pour la diode rouge. Comme développé plus loin, la puissance optique de chacune des sources monochromatiques pourra également être pilotée pour moduler la puissance optique du faisceau polychromatique 10. Les faisceaux 7, 8, 9 émis par chacune des sources monochromatiques sont orientés, par exemple, parallèlement les uns aux autres et réfléchis dans une même direction pour former par combinaison le faisceau polychromatique commun 10. La source polychromatique comprend ici en ce sens des éléments optiques semi- transparent, sur une plage de longueur d'onde, tels que des miroirs dichroïque ou lames de combinaison 11, interceptant les faisceaux monochromatiques 7, 8, 9 émis par chacune des sources monochromatiques et les combinant selon la direction du faisceau polychromatique 10. The optical power of each of the monochromatic sources is driven, independently, using the supply current of the laser source or sources. At a given optical power, the color of the polychromatic beam 10 is determined by how a power ratio is established between the different laser diodes. For example, to obtain a white light, the optical powers, in proportion, must be established according to the following distribution: 60% for the green diode, 30% for the blue diode, 10% for the red diode. As further developed, the optical power of each of the monochromatic sources can also be controlled to modulate the optical power of the polychromatic beam 10. The beams 7, 8, 9 emitted by each of the monochromatic sources are oriented, for example, parallel to each other and reflected in the same direction to form by combination the common polychromatic beam 10. The polychromatic source here comprises in this sense elements semi-transparent optics, over a range of wavelengths, such as dichroic mirrors or combination blades 11, intercepting the monochromatic beams 7, 8, 9 emitted by each of the monochromatic sources and combining them in the direction of the polychromatic beam 10 .
De façon plus générale, la source polychromatique 28 est configurée pour former le faisceau polychromatique 10 à partir du ou des faisceaux laser monochromatiques 7, 8, 9 quel que soit le nombre de sources monochromatiques 4, 5, 6 en jeu. En cas de source monochromatique unique, le faisceau 10 est composé du faisceau laser émis par la seule source employée et l'image obtenue sera alors monochrome, composée des différents niveaux de puissances optiques appliquées à chacun des points qui la compose, selon un dégradé de ladite couleur. En cas de pluralité de sources monochromatiques, typiquement les trois sources 4, 5, 6 évoquées plus haut, le faisceau commun 10 qui forme alors le faisceau polychromatique permettra l'établissement d'une image selon un spectre de couleur dont la résolution correspondra à la finesse de pilotage de l'alimentation desdites sources monochromatiques 4, 5, 6. More generally, the polychromatic source 28 is configured to form the polychromatic beam 10 from the monochromatic laser beam (s) 7, 8, 9 irrespective of the number of monochromatic sources 4, 5, 6 involved. single monochromatic, the beam 10 is composed of the laser beam emitted by the only source used and the resulting image will then be monochrome, composed of the different levels of optical power applied to each of the points that compose it, according to a gradient of said color. In the case of a plurality of monochromatic sources, typically the three sources 4, 5, 6 mentioned above, the common beam 10 which then forms the polychromatic beam will allow the establishment of an image according to a color spectrum whose resolution will correspond to the fineness of control of the supply of said monochromatic sources 4, 5, 6.
Dans un mode de réalisation, le système de projection vidéo comprend aussi des moyens 13 d'atténuation, situés en aval de la ou des sources 4, 5, 6, permettant de faire varier la puissance optique du faisceau lumineux 10. Autrement dit, une couleur et/ou une intensité étant conférées au faisceau polychromatique 10 par le contrôle de l'alimentation en courant des sources monochromatiques, les moyens 13 d'atténuation permettent de faire varier la puissance optique du ou des faisceaux 7, 8, 9, 10. On pourra en particulier adapter la puissance optique du faisceau à des conditions de roulage diurne et des conditions de roulage nocturne, pour l'application du système dans un affichage tête haute de véhicule automobile. In one embodiment, the video projection system also comprises attenuation means 13 situated downstream of the source or sources 4, 5, 6, making it possible to vary the optical power of the light beam 10. In other words, a color and / or an intensity being conferred on the polychromatic beam 10 by controlling the power supply of the monochromatic sources, the attenuation means 13 make it possible to vary the optical power of the beam (s) 7, 8, 9, 10. In particular, the optical power of the beam can be adapted to daytime running conditions and night driving conditions, for the application of the system. in a head-up display of a motor vehicle.
La source polychromatique 28 pourra comprendre des moyens de pilotage de l'alimentation en courant des sources monochromatiques. Comme évoqué plus haut, ils pourront permettre un choix de la couleur du faisceau 10. The polychromatic source 28 may comprise means for controlling the power supply of the monochromatic sources. As mentioned above, they may allow a choice of the color of the beam 10.
Plus précisément, les moyens de pilotage sont configurés, par exemple, pour assurer une régulation linéaire en courant de la puissance optique des faisceaux laser monochromatiques 7, 8, 9 de façon à assurer le choix de couleur du faisceau polychromatique 10, selon une proportion de puissance optique attribuée à chacun des faisceaux laser monochromatiques 7, 8, 9. On pourra, par exemple, prévoir un codage de la couleur sur six bits, correspondant à soixante quatre niveaux de puissance optique pour chacun desdits faisceaux laser monochromatiques 7, 8, 9. Les moyens de pilotage pourront aussi être configurés pour assurer un complément de réglage de la puissance optique du faisceau lumineux. On peut de la sorte atteindre un taux d'atténuation particulièrement élevé. More specifically, the control means are configured, for example, to provide a linear current regulation of the optical power of the monochromatic laser beams 7, 8, 9 so as to ensure the color selection of the polychromatic beam 10, in a proportion of optical power allocated to each of the monochromatic laser beams 7, 8, 9. For example, it is possible to provide six-bit color coding, corresponding to sixty four optical power levels for each of said monochromatic laser beams 7, 8, 9 The control means may also be configured to provide additional adjustment of the optical power of the light beam. In this way, a particularly high attenuation rate can be achieved.
Plus précisément, les moyens de pilotage sont configurés pour assurer une régulation par modulation de largeur d'impulsion de la puissance optique des faisceaux laser monochromatiques 7, 8, 9 de façon à réaliser le complément de réglage de la puissance optique du faisceau polychromatique 10, notamment selon un facteur d'atténuation compris entre 5 et 20, en particulier d'environ 10. More precisely, the control means are configured to provide pulse width modulation regulation of the optical power of the monochromatic laser beams 7, 8, 9 so as to perform the additional adjustment of the optical power of the polychromatic beam 10. in particular according to an attenuation factor of between 5 and 20, in particular of approximately 10.
On peut de la sorte régler la couleur et/ou la puissance optique du faisceau polychromatique 10. Les moyens de pilotage comprennent, par exemple, un micro contrôleur, non représenté.  In this way, it is possible to adjust the color and / or the optical power of the polychromatic beam 10. The control means comprise, for example, a microcontroller, not shown.
Comme illustré à la figure 4 l'invention concerne aussi un afficheur tête haute comprenant un système 100 de projection vidéo selon l'invention. Le système de projection 100 comprend en outre des moyens 102 de formation d'une image à partir du faisceau lumineux 18 émis par le dispositif d'émission 1. Les moyens 102 de formation d'image comprennent des moyens de balayage comme, par exemple, un générateur de balayage 110 dont la fonction est de déplacer horizontalement et verticalement le faisceau lumineux 18 en vue de réaliser un balayage selon une fréquence donnée, égale à 60 Hz à titre d'exemple non limitatif. Le générateur de balayage 110 comprend, notamment, un miroir à balayage à système micro-électromécanique (ci-après appelé miroir MEMS) sur lequel le faisceau lumineux 18 se réfléchit en un faisceau de balayage 103. Un tel miroir MEMS présente par exemple un diamètre de 1 mm2. Le miroir MEMS est apte à tourner autour de deux axes de rotation pour réaliser un balayage, par exemple à la fréquence de rafraîchissement de 60 Hz, d'un écran diffuseur 111 des moyens 102 de formation d'une image. Ladite image se forme alors sur le diffuseur 111. Alternativement, le miroir MEMS peut être remplacé par deux miroirs plans et déplaçables, dont les mouvements sont associés. L'un de ces miroirs peut être dédié à un balayage selon un axe horizontal alors que l'autre miroir peut être dédié à un balayage selon un axe vertical. As illustrated in FIG. 4, the invention also relates to a head-up display comprising a video projection system 100 according to the invention. The projection system 100 further comprises means 102 for forming an image from the light beam 18 emitted by the transmission device 1. The image forming means 102 comprise scanning means such as, for example, a scanning generator 110 whose function is to move the light beam 18 horizontally and vertically in order to perform a scanning at a given frequency, equal to 60 Hz as a non-limiting example. The scanning generator 110 comprises, in particular, a scanning mirror with a microelectromechanical system (hereinafter referred to as the MEMS mirror) on which the light beam 18 is reflected in a scanning beam 103. Such a MEMS mirror has, for example, a diameter 1 mm 2 . The MEMS mirror is able to rotate around two axes of rotation to perform a scan, for example at the refresh rate of 60 Hz, a diffuser screen 111 of the means 102 for forming an image. Said image is then formed on the diffuser 111. Alternatively, the MEMS mirror can be replaced by two plane and movable mirrors, whose movements are associated. One of these mirrors can be dedicated to a scan along a horizontal axis while the other mirror can be dedicated to a scan along a vertical axis.
Le diffuseur 111 où se forme l'image pourra être un écran de projection transparent à structure complexe pour une projection par transparence. Il pourra alternativement être translucide. Il est réalisé, par exemple, en verre, notamment dépoli, ou en polycarbonate. A titre d'exemple, l'écran diffuseur est du type à pupille de sortie (Exit Pupil Expander en anglais). Il permet de disposer d'un cône d'observation élargi. Il s'étend dans un plan traversé par le faisceau lumineux, l'image résultant de ce faisceau de balayage 103 étant formée dans le plan d'une face de l'écran diffuseur 111. Cet écran diffuseur reçoit le faisceau de balayage 103. Il est agencé pour provoquer une dispersion de ce faisceau de balayage 103 selon un secteur angulaire donné, par exemple égal à 30° par rapport à la direction du faisceau de balayage 103 au moment où il vient frapper l'écran diffuseu r 111. Pour ce faire, selon un exemple non limitatif, une face 112 de l'écran diffuseur est rugueuse, en ce sens qu'elle comporte des aspérités qui provoquent la dispersion du faisceau de balayage 103. La face rugueuse 112 correspond à celle par laquelle le faisceau sort, c'est-à-dire la face sur laquelle l'image se forme. The diffuser 111 where the image is formed may be a transparent projection screen with a complex structure for projection by transparency. It can alternatively be translucent. It is made, for example, of glass, especially frosted, or polycarbonate. By way of example, the diffuser screen is of the exit pupil type (Exit Pupil Expander). It allows to have an expanded observation cone. It extends in a plane traversed by the light beam, the image resulting from this scanning beam 103 being formed in the plane of a face of the diffuser screen 111. This diffuser screen receives the scanning beam 103. is arranged to cause a dispersion of this scanning beam 103 according to a given angular sector, for example equal to 30 ° with respect to the direction of the scanning beam 103 when it strikes the diffusor screen 111. To do this , according to a nonlimiting example, a face 112 of the diffuser screen is rough, in that it has asperities that cause the dispersion of the scanning beam 103. The rough face 112 corresponds to that through which the beam comes out, that is to say the face on which the image is formed.
Selon une autre variante non illustré, lesdits moyens de formation d'image ne comportent pas de générateur de balayage, tel que précédemment décrit, mais une matrice de micro miroirs (aussi appelée Digital micro mirrors Systems en anglais). Dans cette configuration, l'image est formée au niveau de la matrice à micro miroirs puis projetée sur l'écran diffuseur. De manière générale, on place une optique de projection entre la matrice et l'écran. Chaque micro miroir correspond à un pixel de l'image. Dans ce mode de réalisation, l'image n'est pas formée sur l'écran diffuseur pour la première fois, mais reçoit une image préalablement formée sur la matrice à micro miroirs. According to another variant not illustrated, said image forming means do not include a scanning generator, as described above, but a matrix of micro mirrors (also called Digital micro mirrors Systems in English). In this configuration, the image is formed at the level of the mirror array and then projected onto the diffuser screen. In general, a projection optics is placed between the matrix and the screen. Each micro mirror corresponds to a pixel of the image. In this embodiment, the image is not formed on the diffuser screen for the first time, but receives an image previously formed on the mirror array.
Il est à noter que les moyens d'atténuation 13 de la figure 3 pourront être disposés en amont des moyens 102 de formation d'image. Ils pourront encore être en aval. Dans une variante, ils pourront être placés entre le générateur de balayage 110 ou la matrice de micro miroirs, d'une part, et, d'autre part, l'écran diffuseur 111. It should be noted that the attenuation means 13 of FIG. 3 may be arranged upstream of the imaging means 102. They can still be downstream. In a variant, they may be placed between the scanning generator 110 or the micro-mirror array, on the one hand, and the diffuser screen 111, on the other hand.
Le système de projection pourra encore comprendre différents miroirs 104, 106 plans ou concaves de sorte à focaliser les faisceaux vers l'écran diffuseur 111, placés notamment sur la trajectoire du faisceau de balayage 103. The projection system may also comprise different mirrors 104, 106 planes or concave so as to focus the beams to the diffuser screen 111, placed in particular on the trajectory of the scanning beam 103.
L'invention concerne encore un afficheur, notamment tête haute, comprenant un système de projection 100 selon l'une quelconque des variantes détaillées ci-dessus. The invention also relates to a display, including a head-up, comprising a projection system 100 according to any of the variants detailed above.
En aval de l'écran diffuseur 111 selon le sens de déplacement du faisceau lumineux, l'afficheur comprend au moins une lame semi-réfléchissante 126 et un dispositif de réflexion 125 interposé sur le trajet de l'image entre l'écran diffuseur 111 et la lame semi-réfléchissante 126, le dispositif de réflexion 125 comprenant un ou plusieurs miroirs plans ou concaves, comme représenté sur la figure 4. Sur cette figure, le trajet de l'image est symbolisé par trois flèches 30 en pointillé qui se réfléchissent sur le dispositif de réflexion 125 avant de s'afficher à travers la lame semi-réfléchissante 126. Cette dernière permet un grossissement et/ou, par transparence, un affichage de l'image au-delà de ladite lame semi-réfléchissante, notamment au-delà du pare-brise du véhicule équipé, au niveau d'un écran virtuel 130, obtenu à l'aide de la lame semi- réfléchissante 126. Cette lame semi-réfléchissante présente un pouvoir de réflexion au moins égal àDownstream of the diffuser screen 111 according to the direction of movement of the light beam, the display comprises at least one semi-reflective plate 126 and a reflection device 125 interposed on the path of the image between the diffuser screen 111 and the semi-reflecting plate 126, the reflection device 125 comprising one or more planar or concave mirrors, as shown in FIG. 4. In this figure, the path of the image is symbolized by three dotted arrows 30 which are reflected on the reflection device 125 before being displayed through the semi-reflecting blade 126. The latter allows a magnification and / or, by transparency, a display of the image beyond said semi-reflective plate, in particular beyond the windshield of the equipped vehicle, at a virtual screen 130, obtained using the semi-reflecting blade 126. This semi-reflective blade -reflective has a power of reflection at least equal to
20%, ce qui permet à l'utilisateur de voir au travers de la lame la route empruntée par le véhicule, tout en bénéficiant d'une luminosité élevée permettant de voir l'image affichée. De manière alternative, l'affichage de l'image peut avoir lieu au niveau du pare-brise du véhicule équipé dudit afficheur. 20%, which allows the user to see through the blade the route taken by the vehicle, while enjoying a high brightness to see the image displayed. Alternatively, the display of the image can take place at the windshield of the vehicle equipped with said display.
Comme illustré à la figure 5, l'invention concerne aussi un dispositif d'éclairage adaptatif pour véhicule automobile, comprenant un système 100 de projection vidéo selon l'invention. Comme sur la figure 4, les mêmes références se rapportant aux mêmes éléments, le système 100 de projection vidéo comprend le dispositif d'émission 1, fournissant le faisceau combiné 18, et les moyens 102 de formation d'image. Les moyens 102 comprennent à leur tour les moyens de balayage 110, fournissant un faisceau de balayage 103, et des moyens optique référencés 118, du type des miroirs 104, 106 de la figure 4, destiné à focaliser le faisceau de balayage sur un dispositif 113. Le faisceau en sortie des moyens optiques 118 porte la référence 115. As illustrated in FIG. 5, the invention also relates to an adaptive lighting device for a motor vehicle, comprising a video projection system 100 according to the invention. As in FIG. 4, the same references relating to the same elements, the video projection system 100 comprises the transmission device 1, providing the combined beam 18, and the imaging means 102. The means 102 in turn comprise the scanning means 110, providing a scanning beam 103, and optical means referenced 118, the type of the mirrors 104, 106 of Figure 4, for focusing the scanning beam on a device 113. The beam at the output of the optical means 118 has the reference 115.
L'élément 113 est un dispositif de conversion de longueur d'onde comme par exemple une plaque de phosphore, ou plus exactement une plaque sur laquelle a été déposée une couche continue et homogène de phosphore. The element 113 is a wavelength conversion device such as a phosphor plate, or more exactly a plate on which has been deposited a continuous and homogeneous layer of phosphorus.
De façon connue, chaque point de la plaque du dispositif de conversion de longueur d'onde 113 recevant le faisceau 115 réémet alors un faisceau 116, illustré en pointillés, de longueur d'onde différente, et notamment une lumière qui peut être considérée comme « blanche », c'est-à-dire qui comporte une pluralité de longueurs d'onde entre environ 400 nanomètres et 800 nanomètres, c'est-à-dire comprises dans le spectre de la lumière visible. Cette émission de lumière se produit, selon un diagramme d'émission lambertienne, c'est-à-dire avec une intensité lumineuse uniforme dans toutes les directions. In known manner, each point of the plate of the wavelength converting device 113 receiving the beam 115 then re-emits a beam 116, illustrated in dotted lines, of different wavelength, and in particular a light which can be considered as " white ", that is to say which has a plurality of wavelengths between about 400 nanometers and 800 nanometers, that is to say included in the spectrum of visible light. This emission of light occurs, according to an emission diagram Lambertian, that is to say with a uniform luminous intensity in all directions.
De préférence, le phosphore est déposé sur un substrat réfléchissant pour le rayonnement laser. De cette manière, on est assuré que le rayonnement laser qui n'aurait pas rencontré de grain de phosphore avant d'avoir traversé complètement la couche de phosphore, pourra rencontrer un grain de phosphore après avoir été réfléchi par le substrat.  Preferably, the phosphor is deposited on a reflective substrate for the laser radiation. In this way, it is ensured that the laser radiation which would not have encountered any phosphorus grain before having completely passed through the phosphor layer, could meet a grain of phosphorus after having been reflected by the substrate.
De préférence également, le substrat est choisi dans les matériaux bons conducteurs thermiquement. Une telle disposition permet d'assurer une faible température du phosphore, ou au moins d'éviter que sa température ne devienne excessive. L'efficacité, c'est-à-dire le rendement de conversion du phosphore, est alors maximale.  Also preferably, the substrate is selected from materials that are good thermal conductors. Such an arrangement makes it possible to ensure a low temperature of the phosphorus, or at least to prevent its temperature from becoming excessive. The efficiency, that is to say the conversion efficiency of phosphorus, is then maximum.
On est donc ainsi assuré d'avoir un rendement maximal de conversion entre le rayonnement laser et la lumière blanche.  It is thus ensured to have a maximum conversion efficiency between the laser radiation and the white light.
De préférence encore, la surface du dispositif de conversion de longueur d'onde est constituée d'une couche continue et homogène de phosphore. En effet, la partition de la plaque de phosphore en éléments distincts ne permet pas d'obtenir la précision souhaitée dans la réémission de lumière blanche, particulièrement au niveau des points situés à la limite entre deux éléments de phosphore.  More preferably, the surface of the wavelength conversion device consists of a continuous and homogeneous layer of phosphorus. Indeed, the partition of the phosphor plate into separate elements does not achieve the desired accuracy in the retransmission of white light, particularly at the points at the boundary between two phosphorus elements.
La plaque de phosphore 113 est située au voisinage immédiat du plan focal d'un système optique 114 d'imagerie, qui forme alors à l'infini une image de la plaque de phosphore 113, ou plus exactement des points de cette plaque qui émettent de la lumière blanche en réponse à l'excitation lumineuse qu'ils reçoivent. En d'autres termes, le système optique d'imagerie 114 forme un faisceau lumineux 117, également illustré en pointillés, avec la lumière émise par les différents points de la plaque de phosphore illuminés par le rayonnement 115. The phosphor plate 113 is located in the immediate vicinity of the focal plane of an imaging optical system 114, which then forms at infinity an image of the phosphor plate 113, or more exactly points of this plate that emit white light in response to the bright excitement they receive. In other words, the imaging optical system 114 forms a light beam 117, also shown in dotted lines, with the light emitted by the various points of the phosphor plate illuminated by the radiation 115.
Le faisceau lumineux 117 émergeant du système d'imagerie 114 est ainsi directement fonction des rayons lumineux 116 émis par la plaque de phosphore 113, eux-mêmes fonction directement du rayonnement 115 qui balaye cette plaque 113. Une unité de commande (non représentée) pilote les différents composants du système selon l'invention en fonction de la photométrie désirée du faisceau lumineux 117. En particulier, l'unité de commande pilote simultanément : The light beam 117 emerging from the imaging system 114 is thus directly a function of the light rays 116 emitted by the phosphor plate 113, themselves directly dependent on the radiation 115 which scans the plate 113. A control unit (not shown) controls the various components of the system according to the invention as a function of the desired photometry of the light beam 117. In particular, the control unit simultaneously controls:
- Les moyens de balayage 110 pour que le faisceau 115 balaye successivement tous les points de la plaque de phosphore 113, et  The scanning means 110 for the beam 115 to successively scan all the points of the phosphor plate 113, and
Le dispositif d'émission 1 pour moduler l'intensité du faisceau 115.  The transmission device 1 for modulating the intensity of the beam 115.
Il est ainsi possible d'éclairer la plaque de phosphore 113 avec le faisceau 115 de manière à former sur cette plaque 113 une image, cette image étant formée d'une succession de lignes formées chacune d'une succession de points plus ou moins lumineux, de la même manière qu'une image sur un écran de télévision. It is thus possible to illuminate the phosphor plate 113 with the beam 115 so as to form on this plate 113 an image, this image being formed of a succession of lines each formed of a succession of more or less bright points, in the same way as an image on a television screen.
La modulation d'intensité peut être effectuée de façon continue, l'intensité croissant ou décroissant continûment entre une valeur minimale et une valeur maximale. Elle peut également être effectuée de façon discrète, l'intensité variant par sauts d'une valeur à une autre, entre une valeur minimale et une valeur maximale. Dans les deux cas, on pourra prévoir que la valeur minimale sera nulle, correspondant à une absence de lumière. The intensity modulation can be performed continuously, the intensity increasing or decreasing continuously between a minimum value and a maximum value. It can also be performed discretely, the intensity varying in jumps from one value to another, between a minimum value and a maximum value. In both cases, it can be expected that the minimum value will be zero, corresponding to an absence of light.
Chaque point de la plaque de phosphore 113 ainsi éclairé par le faisceau 115 émet de la lumière blanche 116, avec une intensité qui est directement fonction de l'intensité du faisceau qui éclaire ce point, l'émission s'effectuant selon un diagramme d'émission lambertienne. Each point of the phosphor plate 113 thus illuminated by the beam 115 emits white light 116, with an intensity which is a direct function of the intensity of the beam which illuminates this point, the emission being effected according to a diagram of Lambertian emission.
La plaque de phosphore 113 peut alors être considérée comme une source de rayonnement secondaire, constituée d'une image lumineuse, dont le système optique d'imagerie 114 forme une image à l'infini, par exemple sur un écran placé à distance dans l'axe du système optique 114 et perpendiculairement à cet axe. L'image sur un tel écran est la matérialisation du faisceau lumineux émis par le système optique 114. De la sorte, le faisceau 117 forme un faisceau d'éclairage pour véhicule automobile qui est adaptatif, c'est-à-dire dont la puissance lumineuse est commandabie point par point de façon à être adaptée à l'environnement du véhicule. The phosphor plate 113 can then be considered as a source of secondary radiation, consisting of a light image, whose optical imaging system 114 forms an image at infinity, for example on a screen placed at a distance in the axis of the optical system 114 and perpendicular to this axis. The image on such a screen is the materialization of the light beam emitted by the optical system 114. In this way, the beam 117 forms a lighting beam for a motor vehicle which is adaptive, that is to say whose light output is controllable point by point so as to be adapted to the environment of the vehicle.

Claims

REVENDICATIONS
Système de projection vidéo par balayage de faisceau lumineux, caractérisé en ce qu'il comprend un dispositif d'émission (1) d'un faisceau lumineux (18) modulé par un signal vidéo, et des moyens de balayage (20, 110) aptes à dévier ledit faisceau lumineux (18) pour permettre la formation d'une image vidéo (22), le dispositif d'émission (1) comprenant au moins deux sources lumineuses (24, 25) distinctes émettant chacune un sous-faisceau lumineux (14, 15) de polarisation sensiblement rectiligne, distincte de l'autre, et un dispositif de recombinaison (12) configuré pour former ledit faisceau lumineux (18) par combinaison des deux sous-faisceaux lumineux (14, 15), en direction des moyens de balayage (20). Video projection system by scanning light beam, characterized in that it comprises a device (1) for transmitting a light beam (18) modulated by a video signal, and scanning means (20, 110) capable of deflecting said light beam (18) to allow formation of a video image (22), the transmitting device (1) comprising at least two distinct light sources (24, 25) each emitting a light sub-beam (14); , 15) of substantially straight polarization, distinct from the other, and a recombination device (12) configured to form said light beam (18) by combining the two sub-light beams (14, 15), in the direction of the light source means. scanning (20).
Système de projection selon la revendication 1, caractérisé en ce que le dispositif de recombinaison (12) est un prisme de recombinaison. Projection system according to claim 1, characterized in that the recombination device (12) is a recombination prism.
Système de projection selon la revendication précédente, caractérisé en ce que le prisme de recombinaison est un des prismes suivant : Projection system according to the preceding claim, characterized in that the recombination prism is one of the following prisms:
prisme de Wollaston,  Wollaston prism,
prisme de Glan-Taylor,  Glan-Taylor prism,
prisme de Glan-Thompson,  Glan-Thompson prism,
prisme de Nicol.  Nicol's prism.
Système de projection selon l'une des revendications précédentes, caractérisé en ce que les deux sous-faisceaux lumineux (14, 15) ont une polarisation perpendiculaire l'une à l'autre. Projection system according to one of the preceding claims, characterized in that the two sub-light beams (14, 15) have a polarization perpendicular to each other.
Système de projection selon l'une des revendications précédentes, caractérisé en ce que les sources lumineuses (24, 25) sont des sources lasers. Projection system according to one of the preceding claims, characterized in that the light sources (24, 25) are laser sources.
6. Système de projection selon la revendication précédente, caractérisé en ce que les sources lasers ont des spectres fréquentiels de puissance différents dans une même bande de fréquence étroite. 6. Projection system according to the preceding claim, characterized in that the Laser sources have different power spectra of different power in the same narrow frequency band.
Système de projection selon l'une des revendications précédentes, caractérisé en ce que les sous-faisceaux lumineux (14, 15) sont des sous-faisceaux polychromatiques et en ce que les sources lumineuses (24, 25) sont des sources polychromatiques. Projection system according to one of the preceding claims, characterized in that the sub-light beams (14, 15) are polychromatic sub-beams and that the light sources (24, 25) are polychromatic sources.
Système de projection selon la revendication précédente, caractérisé en ce que chaque source lumineuse polychromatique comprend trois sources lumineuses (4, 5, 6) monochromatiques, une source rouge émettant un faisceau lumineux rouge, une source verte émettant un faisceau lumineux vert et une source bleue émettant un faisceau lumineux bleu, les faisceaux rouge, vert et bleu étant combinés pour former chaque sous-faisceau polychromatique. 9. Afficheur, notamment afficheur tête haute, caractérisé en ce qu'il comprend un système de projection (100) selon l'une des revendications précédentes. Projection system according to the preceding claim, characterized in that each polychromatic light source comprises three monochromatic light sources (4, 5, 6), a red source emitting a red light beam, a green source emitting a green light beam and a blue source emitting a blue light beam, the red, green and blue beams being combined to form each polychromatic sub-beam. 9. Display, including head-up display, characterized in that it comprises a projection system (100) according to one of the preceding claims.
10. Dispositif d'éclairage adaptatif pour véhicule automobile, caractérisé en ce qu'il comprend un système de projection selon l'une des revendications précédentes. 10. Adaptive lighting device for a motor vehicle, characterized in that it comprises a projection system according to one of the preceding claims.
11. Dispositif d'éclairage selon la revendication 10, caractérisé en ce qu'il comprend en outre un dispositif de conversion de longueur d'onde sur lequel est formée une image par le système de projection, le dispositif de conversion émettant un faisceau lumineux d'éclairage modulé en fonction de ladite image. 11. Illumination device according to claim 10, characterized in that it further comprises a wavelength conversion device on which an image is formed by the projection system, the conversion device emitting a light beam of light. modulated lighting according to said image.
12. Procédé de projection vidéo par balayage de faisceau lumineux, caractérisé en ce qu'il comprend une étape d'émission d'un faisceau lumineux (18) modulé par un signal vidéo, une étape de déviation dudit faisceau lumineux (18) par balayage pour permettre la formation d'une image vidéo (22), l'étape d'émission d'un faisceau lumineux (18) étant précédée d'une étape de combinaison de deux sous-faisceaux lumineux (14, 15) distincts et de polarisation sensiblement rectiligne, distinctes l'une de l'autre, pour former ledit faisceau lumineux (18). 12. A method of video projection by scanning light beam, characterized in that it comprises a step of emitting a light beam (18) modulated by a video signal, a step of deflecting said light beam (18) by scanning to allow the formation of a video image (22), the step of emitting a light beam (18) being preceded by a step of combining two distinct sub-beams of light (14, 15) and polarization substantially rectilinear, distinct one on the other, to form said light beam (18).
EP14828186.8A 2013-12-30 2014-12-18 Scanned light beam video projection system and method, automotive vehicle head-up display and adaptive lighting device using such a system Withdrawn EP4154047A1 (en)

Applications Claiming Priority (2)

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FR1363697A FR3016053B1 (en) 2013-12-30 2013-12-30 SYSTEM AND METHOD FOR LIGHT BEAM SCANNING VIDEO PROJECTION, HIGH HEAD DISPLAY, AND ADAPTIVE LIGHTING DEVICE FOR MOTOR VEHICLE USING SUCH A SYSTEM.
PCT/FR2014/000295 WO2015101725A1 (en) 2013-12-30 2014-12-18 Scanned light beam video projection system and method, automotive vehicle head-up display and adaptive lighting device using such a system

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FR3016053A1 (en) 2015-07-03
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JP2017504833A (en) 2017-02-09
WO2015101725A1 (en) 2015-07-09

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